size_t strxfrm(char *restrict s1, const char *restrict s2, size_t n);
size_t strxfrm_l(char *restrict s1, const char *restrict s2,
size_t n, locale_t locale);
IEEE Std 1003.1-2017
functions shall transform the string pointed to by s2 and place the resulting string into the array pointed to by
s1. The transformation is such that if
strcmp() is applied to two transformed
strings, it shall return a value greater than, equal to, or less than
0, corresponding to the result of
respectively, applied to the same two original strings
with the same locale. No more than n bytes are
placed into the resulting array pointed to by s1, including the terminating
NUL character. If n is
0, s1 is
permitted to be a null pointer. If copying takes place between objects that overlap, the behavior is undefined.
strxfrm_l() functions shall not change the setting of
errno if successful.
Since no return value is reserved to indicate an error, an application wishing to check for error situations should set
0, then call
strxfrm_l(), then check
behavior is undefined if the locale argument to
strxfrm_l() is the special locale object
LC_GLOBAL_LOCALE or is not a
valid locale object handle.
Upon successful completion,
strxfrm_l() shall return the length of the transformed string (not including the terminating
If the value returned is n or more, the contents of the array pointed to by s1 are unspecified.
errno but no return value is reserved to indicate an error.
These functions may fail if:
EINVAL- The string pointed to by the s2 argument contains characters outside the domain of the collating sequence.